Kidney Transplant Tied to Reduced Mortality in Sickle Cell Patients

By Lisa Rapaport

March 05, 2021

(Reuters Health) - Although the benefits of kidney transplant are similar for sickle cell patients and those with kidney failure due to other causes, a new study suggests that sickle cell patients are much less likely to receive organs.

Researchers examined data collected from 1998 to 2017 on two cohorts of patients with kidney failure. The first group, a "dialysis cohort," included 1,970 patients with sickle cell and 2.05 million patients with kidney failure from other causes. The second group, a "waitlist cohort," included 507 sickle cell patients and 463,298 with kidney failure due to other conditions who were placed on transplant waiting lists.

Compared to the control groups of patients with kidney failure attributed to other conditions, the patients with sickle cell were significantly more likely to experience dialysis mortality (adjusted hazard ratio 2.14), waitlist mortality (aHR 3.21), and post-transplant mortality (aHR 3.03), researchers report in CJASN.

Both sickle cell patients (HR 0.57) and control patients (HR 0.54) experienced significant, and similar, reductions in mortality when they received transplants. However, sickle cell patients were significantly less likely to receive transplants (HR 0.48) from the time they initiated dialysis than those with kidney failure due to other causes.

"Our first hypothesis was that the sickle cell population is more likely to die while waiting for a kidney, but the sickle cell population was still less likely to receive transplants even after we adjusted for the differences in mortality within our statistical models," said senior study author Tanjala Purnell, associate director of the Johns Hopkins Center for Health Equity in Baltimore.

"This suggests that there could be other systematic disparities that serve as barriers to transplantation for the sickle cell population," Purnell said by email.

When researchers looked just at patients on transplant waitlists, they still found sickle cell patients significantly less likely to receive kidneys (HR 0.82) in analysis that treated death as a censoring event and also restricted controls to patients identified as Black or African American.

One limitation of the study, the authors note, is that mortality associated with transplant was assessed based on waitlisted patients, a status that can be influenced by factors such as regional availability or patient blood type that don't reflect on how likely individual patients are to survive or benefit from transplants.

Another limitation is that the registry data facilitated identification of patients based on the primary cause for kidney failure, so it's possible some sickle cell patients with other comorbidities listed as the primary reason for kidney failure could have been included in control groups.

Sickle cell-related transplant mortality should not be considered in the aggregate transplant mortality due to high-risk disease because this puts sickle cell patients at an unfair disadvantage in consideration for transplant, said Dr. Santosh Saraf, director of translational research at the Sickle Cell Center at the University of Illinois at Chicago.

"Including sickle cell-related transplant mortality in the aggregate mortality statistics leads to barriers in access to care and promotes health inequity in this high-risk population," Dr. Saraf, who wasn't involved in the study, said by email.

SOURCE: https://bit.ly/2O6d4H4 and https://bit.ly/387qwRW CJASN, online February 25, 2021.

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